This is open source code Geiger SD Logger project based on Arduino IDE. The kit includes main board with 16x2 LCD and SD Logger Shield. The link to download source files will be sent to a buyer with the package.

SD Shield has RTC circuit (real time clock), 3.3V level shifter for SD card, Buzzer and micro SD socket. Support connection of Adafruit GPS module or UART logging through RX TX pins. Files on SD card contains CPM readings for each data point, your local date and time, nmea geographical data and total absorbed dose. 400V high voltage for GM Tube produced with PWM. The kit makes clicker sound similar to a “classic” Geiger counter sound.

By default the Arduino Counter Kit sold without a Geiger tube, but you can add SBM-20 / STS-5 GM Tube to your shopping cart.

Radiation SD Logger based on Atmega-328 and programmed with Arduino IDE. SD Shield has SMT parts that require good soldering skills! Atmega microcontroller comes with Arduino IDE bootloader, but you need to upload supplied sketches by yourself.

The kit has basic simple functions to count GM tube events (CPM), calculate gamma radiation DER for ambient background level or for low-moderate radioactive samples and to write the data on SD card. Since it's educational Arduino IDE project, do not rely on its readings in real hazardous situations!

The main benefit of this kit is SD Logger Shield. It support micro SD Cards with capacity 2Gb-8GB. Radiation data stored with 3 files. Each time you starting the counter, it will create a new log files and the older files stay safe on card. Up to 100 files can be created before you need to clear SD memory. LOG.CSV store CPM readings for each data point. The file can be opened with our "Radiation Logger" Windows application for building graph or with any csv editor. LOG.TXT store local date and time, CPM, aborbed dose accumulated since last minute and battery voltage. If GPS module connected, LOG.TXT will also store NMEA geographical data. DOSE.TXT file keeps only total lifetime absorbed dose. User manual describes an example how you can export nmea data to google map and add CPM readings to the map.

The software and hardware where designed to produce tube high voltage with PWM technology. No additional IC's required, everything is controlled with software. By default it programmed to 400V-420V and you can make fine adjust from 350V to 480V.

The kit compatible with many popular Geiger tubes, such as SBM-20, SBM-19, SI-29BG, SI-180G, SBT-9, SBT-11, J305 and more 400V tubes. It suggested to trim HV to the upper plateau limit of the tube. For example set it 480V for SBM-20 on background. This technique will allow to keep HV within tube plateau recommended limits even under moderate-high radiation load.

As you can see on the graph data, the HV PWM converter works fine up to 400uSv/h (0.4mSv/h) equivalent load and it more than enough for most hobby amateur goals.

Current radiation dose in uSv/h or uRn/h units represented on LCD with CPM (counts per minute) readings. You can switch between LCD units with pressing "down" button. If you press "up" button, it will shows clock for several seconds, like a digital watches. RTC needs 3V backup battery CR1220. This battery is included. PCB allows you to use CR2032 backup battery for RTC with other low cost holder type.

Adafruit GPS module can be connected to RX TX pins and selected through sketch settings during firmware uploading. If no GPS presented, you can use RX TX pins for UART logging. CPM value logged through UART to our "Radiation Logger" Windows program. When connected to computer, the kit can be used as nuclear radiation monitoring station for local logs, radmon or xively. It possible to separate SD Shield from the Main Board if kit used only for UART logging.

The counter has smart LCD backlight controlling for saving battery. Backlight will light on when CPM value reach presetted alert threshold or if you press any button. Alert BL pin is combined with LCD backlight and can be connected to additional alert led or drive relay module.

The kit produce clicker sound beeps similar to "classic" Geiger Counter sound. You can mute buzzer with jumper removed. If radiation level is high, the kit inform you with additional sound indication.

Soldering of the Main Board is very easy because of DIP components, but assembling of SD Shield board require SMT parts part soldering. If you need soldered kit please add soldering service to the purchase!